Synthesis of episulfides



Nov. 24,- 1970 mm Jan. ,4. 1966 V R. c. VANDER LINDEN ETAL SYNTHESIS OFQEPISULFIDES 2 Sheets-Sheet 1 FIGURE I EFFECT OF PERCENTAGE YIELD AND SELECTIVITY TO' PROPYLENE EPISULPHIDE AND CONVERSION OF PROPYLENE OXIDE AS A FUNCTION OF REACTANT MOLE RATIO I so.

*- SELECITIVYITY A 'comgsa'slon I YIELD m 2A A 3/! MOLE RATIO cs /c o RONALD 0. VANDER LINDEN JUAN N. SALVA mvzmoas PETER A. C. SMITH M -4yM um" ATTORNEY Nov. 24. 1970- R..C..VANDER LINDEN ETAL 3,542,808

SYNTHESIS OF EPISULFIDES meda h. 1196s '2 Sheets-Sheet 2 v FIGURE 2 REACTION OF PROPYLENE OXIDE WITH CARBON DISULPHIDE YIELD OF PROPYLENE EPISULPHIDE AS A FUNCTION OF REACTION TEMPERATURE m. C N w. m w E 2 V N O C v w O. C a N. 2 .5 O O 3 3a CR E. N E. R 0 U fin v OM m. m w n N W l M w R N w m .8 W 2 WW R M .2 2 .l wQXOLm ZO. \o M402 mQImJDmEu wzw momm .0 04m;

FIGURE 3 I REACTION OF PROPYLENE OXIDE WITH CARBON DISULPHIDE EXTENT OF PROPYLE'NE OXIDE CONVERSION As A FUNCTION OF TEMPERATURE 0.25-0.32 V/ V/HOUR 0.49-0.53 V/V/HOUR zoo REACTION TEMPERATURE, -c.

o 00 m w 2 l 9558 5x0 mzweioE RONALD c. VANDER LINDEN JUAN M. SALVA PETER A. C. SMITH PATENT ATTORNEY United States Patent 3,542,808 SYNTHESIS OF EPISULFIDES Ronald C. Vander Linden and Juan M. Salva, Sarnia, Ontario, and Peter A. C. Smith, Petrolia, Ontario, Canada, assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Jan. 4, 1966, Ser. No. 518,591 Int. Cl. C07d 95/00 US. Cl. 260-327 14 Claims ABSTRACT OF THE DISCLOSURE Episulfide compounds are synthesized by reacting either a saturated or unsaturated epoxide with carbon disulfide or carbonyl sulfide in the presence of a magnesium oxide, magnesium hydroxide, or barium sulfide catalysts. Conventionally the reaction is conducted in the vapor phase at temperatures ranging from 30 to 400 C.

The present invention relates to an improved process for the economic synthesis of episulfides by reacting satu rated or unsaturated epoxides in the vapor phase with carbonyl sulfide, COS, or carbon disulfide, CS More particularly, this invention relates to obtaining high initial selectivities, e.g. up to 70%, along with good conversions, e.g. up to 45%, specifically by conducting the reaction in the presence of magnesium oxide or hydroxide or barium sulfide. Most particularly, in a preferred embodiment this invention relates to carrying out the reaction at temperatures of 30-400 C. in the presence of the following solid catalysts: MgO, Mg(OH) or BaS.

Highly reactive olefin episulfides of the type of ethylene episulfide and propylene episulfide are clearly recognized to be potentially valuable chemical monomers useful for the preparation of various polymers and a variety of other uses. However, volume use of these materials has to the present awaited an economic method for their synthesis. Such an economic synthesis is provided by the present process.

The catalysts of the present invention may be used alone or supported on standard supports such as asbestos, aluminas, activated carbon, etc. Preferably, the supports, if used, are nonacidic or treated, e.g. with anaqueous base, to be nonacidic since cyclic sulfides dimerize to dithiane derivatives when heated with acidic catalysts. The form of the catalyst is preferably granular or pellets.

The catalyst is normally used in an anhydrous condition. However, it has been found that small additions of water tend to increase the'resultant yield of episulfide due to increased conversion of the epoxide at similar levels of episulfide selectivity. Therefore, it is preferable to add water in amounts of about 0.5-2.5 mole percent based on the reactants; about 1.0 mole percent being particularly preferred.

The catalysts may be used as is or they may be pretreated by calcining at temperatures ranging from 150- 450 C. for about 0.5-3.5 hours in a helium atmosphere. Calcining results in the removal of moisture from the catalyst. In the examples set forth below calcined catalysts were utilized in order to limit catalyst hydration, and

therefore maintain reproducible surface areas and reproducible results. Calcining, if used, is preferably carried out under the following conditions:

MgO-about 0.5-2.5 hrs. at about 400-450 C. Mg(OH) -about 0.5-1.0 hrs. at about 150-200" C. BaSabout 0.5-2 hrs. at about ZOO-250 C.

It should be noted that in a continuous reaction an untreated catalyst will usually have its moisture driven off as a result of the reaction temperatures.

Suitable feedstocks for use in the present invention are unsaturated organic epoxide feeds, preferably gaseous feeds or feeds capable of being converted to a gas without decomposition as follows:

(a) C to C preferably C to C branched and straight chain monoolefi'n epoxides including epoxides containing other functional groups such as aryl groups, carboxyl groups, chlorine, fluorine, etc., e.g. epoxides of the following: ethylene, propylene, isobutylene, l-butene, 2- butene, 2-methy1-1-bntene, pentenes, hexenes, heptenes, dodecenes, styrene, oleic acid, etc.

(b) Same range for epoxides of cyclic monoolefins and substituted cyclic monoolefins, and alkyl, aryl, carboxyl, chlorine and fluorine substituted cyclic monoolefins, beginning with the C ring, e.g. epoxides of cyclobutene, cyclopentene, cyclohexene, cyclohepten, cyclooctene, alkyl substituted derivatives thereof, cyclopentenecarboxylic acid, cyclohexenecarboxylic acid, cinnamic acid, etc.

(c) Same range for branched and straight chain unconjugated diolefin epoxides and alkyl, aryl, carboxyl, chlorine and fluorine substituted unconjugated diolefin epoxides beginning with C (allene), e.g. epoxides of 1 -4 pentadiene, 1-5 hexadiene, etc.

(d) Same range for conjugated diolefin epoxides, branched and straight chain, and alkyl, aryl, carboxyl, chlorine and fluorine substituted conjugated diolefin epoxides beginning with C e.g. epoxides of 1-3 butadiene, isoprene, chloroprene, etc.

(e) Same range for conjugated and unconjugated cyclic diolefin epoxides and alkyl, aryl, carboxyl, chlorine and fluorine substituted cyclic diolefin epoxides beginning with the C ring, e.g. epoxides of cyclobutadienes, cyclopen tadienes, cyclohexadienes, cyclohexadienecarboxylic acids, cycloheptadienes and cyclooctadienes.

(f) Same range for noncyclic and cyclic triolefin epoxides and substituted triolefin epoxides including as substituents alkyl groups, aryl groups, carboxyl groups, chlorine, fluorine, etc., beginning with C e.g. epoxides of cycloheptatrienes, cyclooctatrienes, 1,3,5 hexatriene, heptatrienes, etc.

(g) Same range for epoxides of other nonhydrocarbon feeds including fatty acids, furan, thiophene, 1,4-pyrone, alkyland aryl-substituted thiophenes, unsaturated alcohols, e.g. epoxides of allyl alcohol, etc.

The sulfur-containing compound with which the epoxide is reacted may be carbonyl sulfide or carbon disulfide; both of which have been found to yield similar results in the synthesis of episulfides in accordance with this invention.

The present invention may be carried out under the following preferred conditions:

(1) Temperatures in the range of 0 to 500 C., preferably 30 to 400 C., more preferably IOU-250 C., still more preferably -200 C., e.g. C.

(2) Pressures in the range of 0.1 to 50 atmospheres, preferably 1 to 5 atmospheres, e.g. 1 atmosphere.

(3) Mole ratios of COS or CS to epoxide in the range of l/ 10 to 1000/1, preferably 0.5/1 to 100/1, more preferably 1/1 to 10/1, still more preferably 1/1 to 3/1, e.g. 2/1.

(4) Reaction times in the range of 0.1 second to 1 hour, preferably 0.1 minute to 0.25 hour, more preferably 10 seconds to 5 minutes.

(5) Flow rates of 0.05 to 1.0 volumes of feed per volume of catalyst bed per hour, preferably 0.1 to 1.0, and more preferably 0.1 to 0.5, e.g. 0.25.

In a preferred embodiment, the reaction is carried out in a flow reactor having an L/D of 3:1 to 25:1 at reaction times of 3 seconds to 10 minutes. Also, in a preferred embodiment conditions are utilized to obtain high conversions per pass of 50 to 95% and the desired products, e.g. episulfides, are removed from the product by absorption, extraction, etc. The remaining reaction products are recycled to extinction to thereby obtain high overall conversions and yields.

The present invention will be more clearly underratio of 1:1, with a throughput of 1.0 LHSV. The results shown below indicate the relative activity of as a catalyst for promoting episulfide formation:

stood from a consideration of the following examples.

EXAMPLE 1 Selectivity, mols episulfide Yield, mols Reaction of C 0 with CS over varlous oxide catalysts per mol p ony eplsulfide p ene oxide reacted, mol propylene Propylene oxide and carbon disulfide were introduced Percent wide, Percent through rotameters into a vertically mounted pyrex glass Catalyst: reactor (12 /2 inches long by 1 inch ID) contained in a lswgwmz 65 r(OH)z-8Hz0 Nil 0.6 furnace. The laboratory equipment was valved so as to Ba(OH) -8H O Nil 0.9 permit mass chromatographic sampling of both the entering and product gases from the reactor. The flow rates of carbon disulfide and propylene oxide were about 12- EXAMPLE 4 15 and the feactor Packed f' catalyst and Reaction of COS and C 0 at various temperatures over maintained at 280 C. and atmospherlc pressure. The Mgo molar ratio of carbon disulfide to propylene oxide was 1:1. The following results were obtained with various In eqlllpment slmllaf to h used In Example metal oxide catalysts; bonyl sulfide was reacted with propylene oxide over a high purity MgO catalyst (Fisher Certified Reagent). The molar ratio of COS/C 0 was 1.5/1, pressure was atmospheric and the throughput, calculated on a weight selectivity, hourly space velocity basis, was 0.41-0.47 w./w./hour. g g fi f e g g The following results indicate that temperatures of about mi oxide gacigd, 1.181 r l 150 C. produce the best results for this reaction:

percent oxide, percent 43 16 C con- CiS selec- 9 1 30 verted, tivity, 03S yield, Nil Nil percent percent percent Temperature C 100 4s 4s 23 1 N11 49 5e 27 as 33 13 This reaction indicates that carbonyl sulfide and carbon These results Show that only o is a Satisfactory dlsulfide may be used interchangeably in the process of catalyst for Promoting episulfide synthesis according to this invention. Compar son of these results with those of this invention. Example 7, below, indicate that carbonyl sulfide will react more readily than carbon disulfide to form the desired EXAMPLE 2 episulfides. However, CS the less expensive reactant, was utilized to d 'n tl Reaction of CS and C 0 over various hydroxide catalysts etenm 6 ca a yst actlvlty EXAMPLE 5 In equipment similar to that used in Example 1 and at temperatures of 250-280 C. at atmospheric pressure, L1 e test of m reactlon CS2 with C30 CS and propylene oxide in a molar ratio of 1:1 and a In equipment slmllaf to that used 111 Example a llfe throughput of 0.11-0.44 v./v./hr. were reacted over sev- Study of 8 lf Was ucte C rbon disu fide eral sulfide catalysts. The results shown below indicate and Pf py OXlde III a molar H1110 Of 211, and a Space the relative activity of BaS as a catalyst for promoting Velocity f LHSV; Were TQaCted at and episulfide formation as compared with other sulfides: atmospheflc pressure- Flshef Certlfied Reagent grade 8 (8-16 mesh) was used as the catalyst.

Sample period, hr 3rd 10th Selectivity, mols episulfide Yield, mols Conversion of propylene oxide, perccnt.. 25 12 per mol propylepisulfide per Conversion of 082, percent 9 5 ene oxide reacted, mol propylene Selectivity to propylene episulfide, percent 68 percent oxide, percent Yield of propylene episulfide 15 8 Catalyst I l gggzz 60 These results indicate that catalyst activity with re- BaS 3; 4.2 spect to CS and C 0 decreased with time; however, se- Zns N11 lectivity increased slightly. This example shows the feasi- Trace. bility of conducting relatively long-time continuous reactions. 5 EXAMPLE 6 r0ptimization of reaction conditions would increase the Reaction condition parameters with o catalyst episulfide yield over a BaS catalyst.

The same equipment as used in Example 1 was em- EMMPLE 3 ployed to determine the influence of certain reaction 70 parameters, i.e. temperature, mole ratio, and space velocity Reaction of CS and C 0 over various hydroxide catalysts at atmospheric Pressure, on the Conversion (OXide l'eacted/ oxide feed), selectivity (sulfide formed/oxide reacted) In equipment similar to that used in Example 1, and at and yield of episulfide obtained with MgO as the catalyst. a temperature of 150 C at atmospheric pressure, carbon Results obtained are shown in the accompanying drawings. disulfide was reacted with propylene oxide in a molar FIG. 1 shows the yield, episulfide selectivity, and propylene oxide conversion as a function of molar ratio of CS propylene oxide, at 200 C., atmospheric pressure and a space velocity of 0.5 v./v./hr. FIG. 2 shows theepisulfide yield as a function of reaction temperature, and FIG. 3 shows the propylene oxideconversion at two different space velocities as a function of temperature.

Referring to FIG. 1, it can be seen that yield and selectivity increase with increasing molar ratios of carbon disulfide to propylene oxide. Conversion of propylene oxide increases with increasing mole ratio to a maximum between a ratio of 2/ l to 3/1 of CS /C O. It is interesting to note that although the conversion drops oif slightly at a ratio of 3/ 1, the yield increases because of increasing selectivity. FIG. 2 indicates that greater episulfide yields and propylene oxide conversions are obtained at reaction temperatures in the lower end of the preferred range. Similarly, in FIG. 3, greater conversions of propylene oxide are shown at lower temperatures and also at lower space velocities.

EXAMPLE 7 Addition of water to reaction between CS and C 0 In equipment similar to that used in Example 1, carbon disulfide and propylene oxide in a molar ratio of 1:1, were reacted at 280 C. and atmospheric pressure over a 4-10 mesh Fisher Certified Reagent grade MgO catalyst. The throughput of the reactants was 0.11 v./v./hr. The following results indicate the eifect of adding water to the feed for increasing episulfide yield: 4

Conversion of propylene Selectivity, Yield, Water added oxide, percent percent percent None 46 33 15. 2 1 mole percent (0.36 gJhr.) 72 33 24 It should be noted that the selectivity remained constant, but the conversion increased considerably, thereby resulting in greater yields of episulfide. Consequently, it is not necessary to completely dry the catalysts before conducting the reaction.

EXAMPLE 8 Eifect of catalyst calcination on MgO Conversion, Selectivity}, Yield, Pretreatment percent percent percent None 94 20 19 2 hrs. at 400450 (J 46 33 15. 2

This example shows higher conversions with an untreated catalyst, confirming the result of Example 7 where the addition of water to the feed increases the conversion of propylene oxide (since calcination serves to remove thewater).

EXAMPLE 9 Eifect of catalyst calcination on Mg(OH) In equipment similar to-that used in Example 1,' an episulfide synthesis was conducted with an M g(OH) catalyst to determine the effect of catalyst calcination prior to conducting the episulfide synthesis.

6 At 150 C. and atmospheric pressure, CS and C 0 in a molar ratio of 1/1 were fed to the reactor at a throughput of 1.0 LHSV. The results are as shown below:

Conversion, Selectivity, Yield, Pretreatment percent percent percent None 26 34 9. 2 0.75 hrs. at l50170 C- 11 65 6.8

Again, conversion is increased with no catalyst pretreatment, probably due to increased moisture content.

EXAMPLE 10 Reaction of CS with butadiene oxide EXAMPLE 11 Reaction of CS with propylene oxide over 98% MgO catalyst This example shows the versatility of the preferred MgO catalyst. The catalyst was 'ball milled to 4-10 mesh with 2% graphite added to the mixture. CS and C 0 in a 1/1 mole ratio were reacted at 250 C. in equipment similar to that used in Example 1. Conversion of C 0 was 12%, selectivity to episulfide was 44% and the episulfide yield was 5.5%. In a similar experiment a 98% MgO containing 2% graphite was obtained initially. Under the same reaction conditions the C 0 conversion was 22%, the episulfide selectivity was 23%, and the episulfide yield was 5%. The episulfide yield is normally lower at temperatures of about 250 C. and over.

What is claimed is:

1. A process for the synthesis of episulfides which comprises reacting a C2-C12 straight chain or branched chain epoxide with a sulfur compound selected from the group consisting of carbon disulfide and carbonyl sulfide in the vapor phase at a temperature varying from 100 to 250 C. in the presence of from about 0.5 to 2.5 mol percent water, based upon sulfur compound and epoxide, and a solid catalyst selected from the group consisting of mag nesium oxide, magnesium hydroxide and barium sulfide and thereafter recovering an episulfide product.

2. The process of claim 1 wherein said epoxide is propylene oxide.

3. The process of claim 1 in which said reaction is conducted within a reaction zone containing a fixed bed of catalyst and the flow rate of sulfur compound and epoxide feed to said reaction zone is from 0.5 to 1.0 volumes of sulfur compound and epoxide feed per Volume of catalyst per hour.

4. The process of claim 1 wherein said epoxide is an unsaturated epoxide.

5. The process of claim 1 wherein said epoxide is a saturated epoxide.

6. The process of claim 1 in which the catalyst is MgO.

7. The process of claim 1 in which the catalyst is M )2- 8. The process of claim 1 in which the catalyst is BaS.

9. The process of claim 1 in which the mole ratio of the sulfur compound to the epoxide is from 1/1 to 10/ 1.

10. The process for the synthesis of episulfides which comprises reacting a C -C straight chain or branched chain epoxide with a sulfur compound selected from the group consisting of carbon disultide and carbonyl sulfide in the vapor phase at a temperature varying from 100 to 250 C. in the presence of a solid catalyst selected from the group consisting of magnesium hydroxide and barium sulfide and thereafter recovering an episulfide product.

11. The process of claim 14 wherein said epoxide is propylene oxide.

12. The process of claim 10 wherein said epoxide is propylene oxide.

13. The process of claim 10 wherein said catalyst is barium sulfide.

14. The process of claim 10 wherein said reaction is conducted in the presence of from 0.5 to 2.5 mol percent water, based on said sulfur compound and epoxide.

References Cited UNITED STATES PATENTS OTHER REFERENCES Durden et al. Jour. Amer. Chem. Soc., vol. 82, 1960,

JAMES A. PATTEN, Primary Examiner US. Cl. X.R. 260-329 

